The present invention relates to a new and distinct cultivar of Agastache, given the name, ‘Summer Sky’. Agastache is in the family Lamiaceae. This new variety originated from cross was between a dwarf form of Agastache sp. ‘Pink Pop’ (an unpatented plant) as the seed parent and Agastache rugosa ‘Honey Bee Blue’ as the pollen parent. Compared to the seed parent, Agastache sp. ‘Pink Pop’, the new cultivar has violet blue rather than pink flowers. Compared to the pollen parent, Agastache rugosa ‘Honey Bee Blue’ (an unpatented plant), the new cultivar has a much more compact habit, a larger and darker flower, and a less congested inflorescence. Compared to Agastache ‘Blue Fortune’ the new cultivar is shorter.
This plant exhibits the following characteristics that make it unique:                1. Small, compact habit,        2. Violet blue colored flowers in narrow, tight clusters,        3. Dark calyces,        4. A low branching habit,        5. A long bloom time, and        6. Excellent vigor.        
The new variety has been reproduced only by asexual propagation (cuttings and micropropagation). Each of the progeny exhibits identical characteristics to the original plant. Asexual propagation by division and micropropagation as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.